UV detection technology has great advantages for the effective detection of space targets. Due to the immediacy of the space detection target, it is difficult for the detection system to capture the target. When detecting the space target, it is necessary to select appropriate bands and set effective instrument parameters to increase the capture probability of the space target. At the same time, the field experiment process of space target detection by detector is relatively complex and difficult, so it is difficult to obtain such data. In the absence of test data, in order to make the UV detection system can set effective detection band, and ensure the good test and quickly obtain the radiation characteristics of the longrange target, simulation method is used in this paper. In an experimental way, in the case of unknown atmospheric conditions and composition, a model for calculating the near-surface long-range target radiance in UV band is constructed, which simplifies the radiative transmission process of the signal in the atmosphere. In this paper, the radiation of target in UV band is studied, and the mathematical model of radiation calculation is established. The research results have certain engineering application value. In the field test, it is difficult to determine the atmospheric transmittance between the camera and the target due to the lack of estimation of the atmospheric composition at the launch time, which makes it difficult to accurately estimate the radiation of the long-range target at near-surface in the test site. To solve this problem, the ultraviolet (UV) band was divided into two parts, that were target band (240nm~280nm) and background band (300nm~400nm). By simulation, the estimating models of atmospheric transmissivity were separately established in the two bands. And then the long-distance target radiance was estimated only according to the distance for successive two times between the detector and target in a short time. Compared with the radiance of blackbody simulated, the relative error is about 9.87% in the target band, but only 0.11% in the background band. The research can provide technical support for UV detector to effectively detect the long-range target radiance.
{"title":"A practical target radiance estimating method on near-surface long-range","authors":"Feifei Xu, Xiaomao Huang","doi":"10.1117/12.2664528","DOIUrl":"https://doi.org/10.1117/12.2664528","url":null,"abstract":"UV detection technology has great advantages for the effective detection of space targets. Due to the immediacy of the space detection target, it is difficult for the detection system to capture the target. When detecting the space target, it is necessary to select appropriate bands and set effective instrument parameters to increase the capture probability of the space target. At the same time, the field experiment process of space target detection by detector is relatively complex and difficult, so it is difficult to obtain such data. In the absence of test data, in order to make the UV detection system can set effective detection band, and ensure the good test and quickly obtain the radiation characteristics of the longrange target, simulation method is used in this paper. In an experimental way, in the case of unknown atmospheric conditions and composition, a model for calculating the near-surface long-range target radiance in UV band is constructed, which simplifies the radiative transmission process of the signal in the atmosphere. In this paper, the radiation of target in UV band is studied, and the mathematical model of radiation calculation is established. The research results have certain engineering application value. In the field test, it is difficult to determine the atmospheric transmittance between the camera and the target due to the lack of estimation of the atmospheric composition at the launch time, which makes it difficult to accurately estimate the radiation of the long-range target at near-surface in the test site. To solve this problem, the ultraviolet (UV) band was divided into two parts, that were target band (240nm~280nm) and background band (300nm~400nm). By simulation, the estimating models of atmospheric transmissivity were separately established in the two bands. And then the long-distance target radiance was estimated only according to the distance for successive two times between the detector and target in a short time. Compared with the radiance of blackbody simulated, the relative error is about 9.87% in the target band, but only 0.11% in the background band. The research can provide technical support for UV detector to effectively detect the long-range target radiance.","PeriodicalId":258680,"journal":{"name":"Earth and Space From Infrared to Terahertz (ESIT 2022)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121750285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The space-borne infrared (IR) hyperspectral sounder is one important part of benchmark instruments for detection of the tiny change of long-term global climate. The IR sounder should provide irrefutable benchmarking records by measuring the infrared radiance with an ultra-high accuracy of 0.1 K (k=3, or 99% confidence), and tracing it to the Système Internationale (SI) standard for the Kelvin through the Planck function theory. Besides, the IR sounder would also constitute a reference standard, or calibration observatory, in space to inter-calibrate the international fleet of IR sounders onboard weather satellites, especially those are not as well calibrated. The measurement needs to be well-calibrated with the instrument features being eliminated, and it is critical to investigate the possible error sources associated with the sounder design and its radiometric calibration. One calibration error that arises in Fourier Transform Spectrometers (FTS) has been found associated with the spectrally variable instrument responsivity. According to the theoretical analysis of the current radiometric calibration, this error is an intrinsic feature of the FTS instruments, but it will lead to the measurements no longer being served as the standard radiances because of a radiance error introduced in the calibrated spectrum. In this paper, the radiometric errors result from the instrument responsivity effect are revealed by numerical simulations based on the spectral responses for ideal and close-to-real instruments.
星载红外高光谱探测仪是探测全球长期气候微小变化基准仪器的重要组成部分。红外探测仪应提供无可辩驳的基准记录，以0.1 K (K =3，或99%置信度)的超高精度测量红外辐射，并通过普朗克函数理论追踪到开尔文的SI标准。此外，该红外探测仪也可作为参考标准，或校准天文台，在太空中相互校准气象卫星上的国际红外探测仪，特别是那些没有很好校准的卫星。测量需要在消除仪器特征的情况下进行良好的校准，并且研究与测深仪设计及其辐射校准相关的可能误差源至关重要。傅立叶变换光谱仪(FTS)中出现的一个校准误差与光谱可变仪器响应率有关。根据目前辐射校准的理论分析，该误差是FTS仪器的固有特征，但由于在校准光谱中引入了辐射误差，将导致测量结果不再作为标准辐射。本文通过对理想仪器和接近真实仪器的光谱响应进行数值模拟，揭示了仪器响应效应引起的辐射测量误差。
{"title":"The instrumental responsivity effect to the calibrated radiances of infrared hyperspectral benchmark sounder","authors":"Lu Lee, Chengli Qi, L. Ding","doi":"10.1117/12.2665786","DOIUrl":"https://doi.org/10.1117/12.2665786","url":null,"abstract":"The space-borne infrared (IR) hyperspectral sounder is one important part of benchmark instruments for detection of the tiny change of long-term global climate. The IR sounder should provide irrefutable benchmarking records by measuring the infrared radiance with an ultra-high accuracy of 0.1 K (k=3, or 99% confidence), and tracing it to the Système Internationale (SI) standard for the Kelvin through the Planck function theory. Besides, the IR sounder would also constitute a reference standard, or calibration observatory, in space to inter-calibrate the international fleet of IR sounders onboard weather satellites, especially those are not as well calibrated. The measurement needs to be well-calibrated with the instrument features being eliminated, and it is critical to investigate the possible error sources associated with the sounder design and its radiometric calibration. One calibration error that arises in Fourier Transform Spectrometers (FTS) has been found associated with the spectrally variable instrument responsivity. According to the theoretical analysis of the current radiometric calibration, this error is an intrinsic feature of the FTS instruments, but it will lead to the measurements no longer being served as the standard radiances because of a radiance error introduced in the calibrated spectrum. In this paper, the radiometric errors result from the instrument responsivity effect are revealed by numerical simulations based on the spectral responses for ideal and close-to-real instruments.","PeriodicalId":258680,"journal":{"name":"Earth and Space From Infrared to Terahertz (ESIT 2022)","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115037608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The imaging spectrometer monitoring the CO2 content in the atmosphere is mainly divided into the weak CO2 band and the strong CO2 band. Compared with the strong CO2 band, the weak CO2 band has a relatively clean spectrum, less interference from water vapor and other gases, and weaker CO2 absorption, and the instrument can receive stronger groundreflected solar radiation signals. However, the concentration of CO2 in the atmosphere is low. To use this band to detect changes in CO2 concentration, it is necessary to ensure that the detection instrument has a sufficiently high spectral resolution. Using the immersion grating as the dispersive element in the spectrometer can greatly reduce the size and weight of the instrument while achieving high spectral resolution. In this paper, the quartz immersion grating used in the weak CO2 detector is optimized and designed, the groove parameters of the grating are designed and optimized according to the requirements of the weak CO2 detector used, and the rectangle and different bottom angles are designed and optimized in consideration of the actual production error. In the 1.595-1.625 μm band, the duty cycle of the rectangular groove is 0.3-0.35, the groove depth is 560-630 nm, and the TiO2 thickness is 110-120 nm, the diffraction efficiency of the grating is higher than 80%; the duty ratio is 0.4-0.45, When the groove depth is 590-660 nm and the TiO2 thickness is 100-105 nm, the diffraction efficiency of the grating is higher than 80%. When the duty ratio of the trapezoidal groove is 0.3-0.35, the bottom angle of the trapezoid is 82°-86°, the groove depth is 590-630 nm, and the TiO2 thickness is 120-125 nm, the diffraction efficiency of the grating is higher than 80%. When the duty ratio of the trapezoidal groove is 0.4-0.45, the bottom angle of the trapezoid is 82°-86°, the groove depth is 620-670 nm, and the thickness of TiO2 is 105 nm, the diffraction efficiency of the grating is higher than 80%.
{"title":"Study on immersion grating used in weak carbon dioxide band detection spectrometer","authors":"B. Huang, Quan Liu, Nenghua Zhou, Zongqing Wu","doi":"10.1117/12.2665406","DOIUrl":"https://doi.org/10.1117/12.2665406","url":null,"abstract":"The imaging spectrometer monitoring the CO2 content in the atmosphere is mainly divided into the weak CO2 band and the strong CO2 band. Compared with the strong CO2 band, the weak CO2 band has a relatively clean spectrum, less interference from water vapor and other gases, and weaker CO2 absorption, and the instrument can receive stronger groundreflected solar radiation signals. However, the concentration of CO2 in the atmosphere is low. To use this band to detect changes in CO2 concentration, it is necessary to ensure that the detection instrument has a sufficiently high spectral resolution. Using the immersion grating as the dispersive element in the spectrometer can greatly reduce the size and weight of the instrument while achieving high spectral resolution. In this paper, the quartz immersion grating used in the weak CO2 detector is optimized and designed, the groove parameters of the grating are designed and optimized according to the requirements of the weak CO2 detector used, and the rectangle and different bottom angles are designed and optimized in consideration of the actual production error. In the 1.595-1.625 μm band, the duty cycle of the rectangular groove is 0.3-0.35, the groove depth is 560-630 nm, and the TiO2 thickness is 110-120 nm, the diffraction efficiency of the grating is higher than 80%; the duty ratio is 0.4-0.45, When the groove depth is 590-660 nm and the TiO2 thickness is 100-105 nm, the diffraction efficiency of the grating is higher than 80%. When the duty ratio of the trapezoidal groove is 0.3-0.35, the bottom angle of the trapezoid is 82°-86°, the groove depth is 590-630 nm, and the TiO2 thickness is 120-125 nm, the diffraction efficiency of the grating is higher than 80%. When the duty ratio of the trapezoidal groove is 0.4-0.45, the bottom angle of the trapezoid is 82°-86°, the groove depth is 620-670 nm, and the thickness of TiO2 is 105 nm, the diffraction efficiency of the grating is higher than 80%.","PeriodicalId":258680,"journal":{"name":"Earth and Space From Infrared to Terahertz (ESIT 2022)","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121830013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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